In many hospitals large numbers of doses of parenteral products have to be prepared daily, for example intravenous bags and other medications administered intravenously. These doses are usually prepared manually in what is an exacting but tedious responsibility for a highly skilled staff. It is, therefore, an object of this invention to provide an automated dispenser to simplify the manual operations necessary for preparing doses of parenteral products while maintaining the exacting standards set by medical regulatory bodies.
Further, prompt and reliable delivery of parenteral products to the patient is essential to the daily operations of a hospital. Manual delivery can be slow and unreliable, possibly resulting in harm to patients. Pneumatic tube transportation systems are currently used to transfer blood samples, medicines, intravenous bags, viral samples or other biological or chemical matter between locations within a hospital or laboratory quickly and reliably. Thus, it is an object of this invention to combine an automated pneumatic tube system with a robot device apparatus to provide a complete automated system for the efficient processing and delivery of parenteral products within a hospital. Other uses of the present invention include dietary, laboratory, and central supply systems, as well as to prepare and deliver intravenous bags.
Dramatic improvements in industrial productivity and quality have been achieved with the application of robotic technology. Spinoffs of this technology that will impact everyday life include home robots for housecleaning, lawn-mowing and fast food robots. Against this backdrop, hospitals and hospital laboratories across the country are beginning to consider the benefits of robotic automation. Health care traditionally has been a difficult marketplace for automation because of the complexity of the procedures and the potential health risks. Nevertheless, exciting medical applications such as the use of robots as assistants in surgical procedures have recently been described. Robots will have a significant impact on medical care by eliminating mundane chores, reducing the exposure of personnel to AIDS and other infectious diseases, and lowering labor costs.
In confronting increasing pressure to reduce the cost of providing analytical results, many laboratories have centralized their services to conserve resources. By consolidating services, expensive equipment has less idle time and labor is used more cost effectively. However, centralization may adversely affect the sample-to-result turnaround time by increasing the distance of the centralized laboratory from the origin of the specimen. Frequently, analytical results must be obtained in a short time to provide information for rapid assessment of a situation so that corrective actions may be taken. In medical care, for example, the clinical state of a critically ill patient must be assessed and corrected before a life threatening condition occurs. Similarly, in the outpatient clinic, providing results of blood analysis to physicians while the patients are still in the physicians' office is highly desirable because it obviates the need for a return appointment to discuss abnormal laboratory results. In industrial process control, real-time monitoring of the progress of chemical reactions by on-site analytical techniques prevents dangerous conditions or loss of products.
Until now, improvements in the turnaround of results have been obtained either by dedicated rapid specimen transportation systems or by simplifications of analytical techniques that make the specimen analysis faster. Pneumatic tube systems, mobile carts, and robotic messengers have been used with some success to transport specimens rapidly to the central laboratory, or from a central pharmacy to remote stations. The present invention provides a greatly improved delivery system, and is particularly directed to the use of an automated pneumatic tube or other automated system in the distribution and receiving step.
By definition, a robot is any machine that can be programmed to perform any task with human-like skill. Practically, the term robotics refers to programmable devices that can perform a variety of skilled actions by using a combination of mechanical and electronic components. Robots are often considered simply a mechanical extension of the computer. The greatest asset of a robot is that it can be configured to perform a multiplicity of tasks and therefore should wear out before it becomes outmoded. Devices designed for only one repetitive task are referred to as "hard automation," e.g., auto-samplers, pipetters, and all other instrumentation with limited mechanical capabilities or restricted programmability.
Laboratory robots can take many forms, however, three basic configurations of robots are predominately used in the clinical laboratory environment, although many other robots are available that are suitable for the laboratory environment.
Cartesian robots are devices with three linear degrees of freedom. Items can be moved about in a three-dimensional (x,y,z) space, but not rotated. Cartesian robots are the basis for sampling devices in many automated analyzers. However, Cartesian robots have found more versatility in the clinical laboratory as pipetting stations, designed to perform many liquid-handling activities.
An example of a Cartesian robot would be the Biomek pipetting station (Beckman Instruments, Brea, Calif.) where the robot can be programmed to perform various liquid-handling protocols. Cartesian robot-pipetting stations allow placement of a pipette tip at any point in space, within approximately equal to 0.2 mm repeatability, with the capability of aliquoting and diluting specimens and dispensing reagents. Cartesian robot-pipetting stations have as their principal components microprocessor-controlled stepping motors that drive liquid-handling syringes, pipetting arms, and in some units movable sample trays.
The Biomek is a hybrid robot in that it has a series of interchangeable hands that allow it to vary its pipetting capabilities. However, the Biomek cannot mechanically manipulate test tubes. In addition, it comes equipped with a built-in spectrophotometer. The Biomek and other similar pipetting stations can be programmed to perform other useful liquid-handling chores such as washing an antibody-coated bead, or rinsing the wells in a microtiter plate.
Recently the Biomek has been configured to perform a monoclonal solid-phase immunoenzymatic assay for carcinoembryonic antigen (Hybritech Inc., San Diego, Calif.). Because of the Biomek's built-in spectrophotometer, the entire assay, including bead washing and data reduction, is handled automatically.
There are several examples in the clinical laboratory of the use of pipetting stations to perform analytical procedures. Brennan et al demonstrated the use of the Tecan Sampler 505 (Tecan AG, Hombrechtikon, Switzerland) in the screening test for anti. HTLV-III antibodies. The procedure required placing a patient's plasma sample in a rack, after which the pipetting station diluted the plasma 441-fold. A barcode reader and pipette washer were retrofitted to the device to positively identify patients and to eliminate carry-over, respectively. The system operated at approximately the same rate as a trained medical technologist but demonstrated better precision and allowed technologists to perform other tasks.
The cylindrical robot, exemplified by the Zymate robot (Zymark Corp., Boston, Mass.) works in a cylindrical performance envelope. The four degrees of freedom exhibited by cylindrical robots (base rotation, elevation, movement in and out of a plane, and wrist roll) are usually sufficient for most laboratory operations. The major limitation of these robots is the lack of wrist pitch, which would be useful for getting in and out of tight places. Additional flexibility in task performance is obtained by programming the robot to use a series of interchangeable hands (a feature patented by Zymark Inc.). Hand and finger orientation is determined by potentiometric servo motors that allow the robot to "sense" its orientation at all times. This arm is a popular choice for simple repetitive tasks and has been used successfully for many sample-preparation protocols, both in the clinical laboratory and in the pharmaceutical industry.
The use of a cylindrical robotic arm to produce an automated blood-typing system that would be affordable to most laboratories has been investigated. The system consists of an indexing rack for samples, which are identified by a barcode reader. After significant development over several years, the system was described again, with throughput increased from 40 to 104 samples per hour. The device was later commercialized by Microban (Dynatech Laboratories, Chantilly, Va.). The success of robotic applications in the blood bank is due to the production line nature of blood typing. Laboratory services that support blood banks require many repetitive analyses before the blood can be used for transfusion. It has been estimated that, in 1984, 12 million units of whole blood were collected in various medical centers, each unit of which required ABO and Rh typing. The blood-typing process has been automated by some manufacturers, but these units cost greater than $100,000 and so are not accessible to most regional hospitals with small transfusion volumes. Robotic arms not only are less expensive than a dedicated blood-typing instrument but also can be reprogrammed when the laboratory's needs change.
The cylindrical robot has been used in the clinical chemistry laboratory at the Cleveland Clinic Foundation to prepare samples for an HPLC method in a complex series of steps: sample extraction, separation of liquid phases, and injection. These investigators incorporated several Zymate robotic systems into a laboratory for the analysis of antidepressants. Medical technologists were needed to prepare the reagents, to place necessary supplies at the designated locations within reach of the robot, and to evaluate the quality of the final results. The robotic laboratory was placed under a fume hood to eliminate any toxic fumes originating from extracted samples during the evaporation process. The robot completed the drug extractions and made the sample injection into the chromatograph by using a specially designed injection hand. For several years these robots have been performing their repetitive tasks with only minor malfunctions.
The use of a robot to perform preparative immunologic precipitations, with final placement of the samples into a rotor for subsequent analysis has been recently reported. This robotic system, which consisted of a Zymate robot and a Cobas-Bio rotor (Roche Diagnostics, Nutley, N.J.), was the first reported system to combine a clinical analyzer and a laboratory robot. However, placing the rotor in the analyzer and transferring the data to the laboratory computer were performed manually.
The Vancouver General Hospital has automated a highly complex steroid-receptor analysis, using a Zymate robotic system. The estrogen receptor assay ordinarily is a manual procedure, involving many critical steps such as centrifugation, incubation, and subsequent placement of completed samples in scintillation vials. In the automated procedure, the incubation water bath, centrifuge, and supply and reagent stations are placed in a circular pattern around the robotic arm. The reagents, which are particularly labile in this assay, are kept cold in an ice bath. Finished samples are added to scintillation vials by the robotic arm. Because more than one rack of vials is produced in a single uninterrupted robotic procedure, the scintillation vial racks are placed in a tiered holder to allow the robot access to two racks.
A Zymate robot, fitted with exchangeable pipetter hands, has been used to dilute and transfer samples for blood grouping in the blood bank. The robot, configured as a pipetting device, was also used to orient samples for barcode reading. After the robot had performed the liquid handling, a human operator proceeded with additional manual aspects of the test. As discussed earlier, many blood-bank analytical methods are relatively simple and are used in sufficient numbers to warrant a dedicated analyzer.
The most versatile robot available to the clinical laboratory is the articulating robot in that it offers more degrees of freedom than either the Cartesian or the cylindrical robots. The articulating robot has shoulder, elbow, and wrist joints, rotating on a pivoting base. Furthermore, the robot has wrist pitch-and-roll, as well as wrist yaw maneuvers, that allow access to areas often difficult to reach on analytical instruments. Positional accuracy of 0.5 mm or better is obtained by using optically encoded discs that must be set by nesting to a home or zero location each time the robot is turned on. A recent example of a sophisticated articulating robot is from Cyberfluor Inc. (Toronto, Ontario, Canada). The Cyberfluor robot has a high degree of flexibility, with five degrees of freedom. Sample processing is currently the rate-limiting step in most clinical laboratories. Using a robot in conjunction with a clinical centrifuge allows processing of samples as they enter the laboratory. One advantage of an articulating robotic arm is its ability to reach over the rim and into a clinical centrifuge to retrieve samples. For a cylindrical robot to perform this task requires use of a custom-altered centrifuge or a custom-made robotic hand. A novel serial centrifuge has also been developed to separate sera or plasma from formed elements in the blood-collection tube. The single-tube centrifuge will eventually be incorporated into a robotic sample-handling system that should not only speed up laboratory productivity but also reduce risk of exposure to AIDS and hepatitis.
Articulating robots are also beginning to be used in the blood-bank laboratory. One manufacturer of blood-banking automation (Flow Laboratories, McLean, Va.) markets a robot interfaced to various microplate-handling devices (pipetters readers, washers, centrifuges). The entire device (the IROBAL) is enclosed in a protective hood, obviously designed to reduce operator exposure to contaminants.
Establishing control of robot motion to mimic the smooth movement of the human arm with a high degree of repositional precision is a difficult problem addressed by the science of kinematics. Kinematics are applied to the robot in three levels of complexity. First, trajectory planning determines position, velocity, and acceleration for each movement made by the robotic manipulators. Second, inverse kinematics are applied to translate the movements required in the coordinate system into the joint movements required by the particular geometry of the robot being developed. Finally, inverse dynamic equations are applied to establish how the robot moves in response to various applied torques and forces. Each movement of the robot is represented, therefore, by a set of remarkably complex equations, the implementation of which has fortunately been simplified through the use of high-level computer languages.
Robot locomotion is a general term applied to all types of robot movement in which the robot can venture away from a fixed point. Locomotion imparts another degree of freedom to the robot but also allows an increase in the variety of hardware with which a robot can interact. Robots can be made mobile by several methods. Robotic arms can be attached to linear tracks or to a mobile cart. In the case of a mobile cart, the portion of the robot imparts mobility is considered an "Automated Guided or Guidance Vehicle" (AGV). AGVs are either equipped with an automatic onboard guidance system or follow a path on the floor wall or ceiling. Guidance is provided through various sensors, e.g., infrared, video, magnetic, or simple light sensors for reflective tape paths. Equipping AGVs with a robotic component produces a mobile robot. Some robots are being designed to have human-or animal-like gait, so that they may climb stairs, for example. The study of bringing human-or animal-like gait to robotic machines is called bionics.
A recent improvement in robot locomotion is the use of linear tracks. The robotic arms can travel the length of a linear track, either upright or upside down, with positional precision of 0.5 mm. This concept has altered the evolution of laboratory design from circular tables with the fixed robot in the middle, back to the classic laboratory bench stretched along the perimeter of the room. Ergonometric laboratories are now possible, such that either technologists or robots can operate the instruments. Robots that can travel the length of a laboratory bench have performance envelopes (the areas in which the robot can perform useful work) that resemble an elongated hemisphere of a doughnut.
Several attempts at robot locomotion have been tried in the clinical setting. Computer-driven vehicles that move about the hospital corridors picking up specimens and delivering them to the main laboratory have been popularized. Similarly, robotic vehicles that move about the laboratory, returning empty specimen racks to the central specimen-receiving area of the lab have also been designed. Mobile robots that can negotiate the corridors of a hospital for specimen delivery have been investigated by Transitions Research Corp. (TRC, Danbury, Conn.) and Saurer Automation Systems, Inc. (Holland, Mich.). Unlike many mobile robots, the TRC Helpmate does not rely on a guide affixed to the floor. The TRC mobile robot is equipped with infrared, ultrasonic, and vision sensors to acquire information about the environment. With the aid of a preprogrammed knowledge base of the hospital layout, the robot arrives at its destination without colliding with patients or objects in its path. Saurer's AGV follows a fluorescent dye guidepath which may be placed directly onto carpeting.
The mechanical performance of the robot can be enhanced by adding sensor technology on the hands or joints of the robot. Various mechanical and electronic sensor systems may be used, e.g., computerized imaging systems to check for sample integrity and container position for access by a robot. Currently, video systems allow a robot the greatest degree of spatial resolution. Several investigators are looking at the feasibility of tactile sensing in the fingertips of robotic fingers. Tactile sensing approaching that of the human finger is in the foreseeable future.
The advantage of sensor technology is the ability of the robot to respond to changes in the analytical method. With proper sensor technology, closed-loop operation of robots becomes a possibility. Analytical data can be checked by the robot's host computer, which is equipped with an expert system, and corrective measures such as sample re-analysis can be initiated if necessary. Many of these enhancements to increase the intelligence of the robotic system have not been examined in the clinical laboratory setting. However, both the Zymate and Cyberfluor robots have fingers that can sense the presence of absence of objects in their grasp. This feature is helpful if test tubes or syringes are dropped inadvertently during a procedure.
Perhaps the single most important factor that has stimulated the introduction or robotics into the clinical laboratory has been the development of high-level robot programming languages with English language commands. For example, the simple command GOTO MIXER initiates an intricate sequence of steps to drive the robotic arm to the mixing device. Several interfaces away from the user's command, the software generates electronic signals to the robot's motion-control mechanism to coordinate a smooth movement arc that terminates at a precise location near the mixer. Complex algorithms involving robot kinematics translate computer machine-code into signals that control the acceleration after commencing the movement and the deceleration before the robotic arm stops at the mixer. Furthermore, to avoid spilling any liquid, the robotic fingers are held parallel to the work surface throughout the complex series of movements. Elaborate procedures can be developed by combining a series of simple commands, which are programmed and tested individually. The robot can be instructed to pause in a procedure, examine the status of a sensor or instrument, and then proceed through a choice of subsequent programs, depending on the outcome of the test. Programmed intelligence of this sort allows highly adaptive systems for performing many assays.
The integration of the various levels of programing language and the input and output ports of the robotic system are controlled by a high-level robot language. Future robotics software is being directed toward standardization and modularization of the basic operations performed in the clinical laboratory: sample manipulation, liquid handling, separation, conditioning, weighing, measuring, reporting, and storing by use of a modular approach. High-level robotic control languages will reduce the time necessary for assay automation. Intellibotics (Oxnard, Calif.) has used a computer graphics interface to simplify writing robot programs. The programs can be implemented graphically before being used to actually run the robot. Modular programming will allow rapid integration of several basic operation modules into a complete assay procedure with appropriate instrumental status checks. Standardization of interfaces with peripheral hardware (i.e., centrifuge, mixer, and pipetter) will be essential for the rapid incorporation of various sample manipulations in the development of robotically controlled assays.
The term user interface implies a software design that makes many of the complex codes for robotic motion control and data input/output transparent to the user. One should be able to use simple English language commands to train a robot to perform any task within its mechanical performance envelope. Perkin-Elmer Corp., Zymark, and Cyberfluor, Inc. have developed simple-to-use robotic-control languages accessible to most computer programmers. Unfortunately, no robot vendor has simplified all aspects of robotics software. In particular the programing associated with communication with other devices remains incomplete.
The use of digitized images (e.g., a picture of the robot and peripheral equipment on the touch screen computer monitor) should allow the user to point to destinations in the picture to which the robot will then physically move. Graphic image inter-faces should reduce the time needed to train laboratory technologists to implement new procedures. Training a laboratory robot to move to specific coordinates on the robotic work-surface can be effected through either a teaching pendant (a group of switches on a remote control) or directly through the robotic keyboard. The robot is positioned by the trainer to a certain location and then the coordinate is entered into the computer via a switch or press of a key on the keyboard. A second coordinate may then be entered in a similar manner. Using simple commands from the keyboard, one replays the coordinates and the robot will move as instructed. Because robots are inherently blind and without tactile senses, they will collide with any obstacles in the path between the two points. Thus trainers must include a third point in the robot program that will allow a collision-free trajectory. A recent innovation in robotic training is the "limp mode" used by the CRS robot marketed by Cyberfluor. In this mode a robot trainer can simply grasp the robot arm and move it to a location. A press of a button automatically enters the position into the robot software, where it will be repeated once the software routine is started. Some future prospects for robot training may couple hand movements with digitized images of the work surface. The monitor will display a picture of the robotic laboratory from a choice of perspectives (e.g., top or side view). A trainer then moves his or her hands on the computer monitor in the path the robot will take during the execution of a procedure. Imaginative methods to train robots will simplify and accelerate the programming of new procedures. Efficient robotic laboratories use procedures that are reduced to LUOs (laboratory unit operations); these are used repeatedly or recombined in a different order as laboratory procedures change. Creating new procedures is simplified by the modular design of the robotic laboratory. The most basic LUOs encompass the moving of items around the laboratory bench, or manipulation. A subcategory of this LUO is robotic interaction with a matrix. Many designers of robotic software have simplified the steps necessary to define and interact with a matrix, such as a test-tube rack, because retrieving samples is universal to almost all procedures. To be successful, implementation of laboratory robotics requires careful planning, attention to detail, and specialized training of staff and skilled support personnel.
According to the invention there is provided an automated system comprising processing, inspection, and transportation stations for the preparation and delivery of parenteral products to a plurality of stations within a hospital. The system comprises several methods which are currently in the market place. The automated processing of pharmaceutical products via robot devices is not new. Presently employed are robot devices having gripping means presentable to a plurality of stations, each station being adapted to cooperate with the robot device in a sequence of operations such as to produce a measured pharmaceutical dose from a supply of a pharmaceutically acceptable substances, and one of the stations comprising means for locating in parallel a plurality of medical hypodermic syringes for containing a said substance and for operating said syringe. The substance might comprise a medication to be administered to a patient, or a potentially biologically damaging substance, such as a radionuclide or a cytotoxin. The measured dose might be retained in a said syringe, or in a medical vial. Preferably, means are provided for controlling the apparatus in a predetermined sequence of operations.
Sterility is an essential characteristic of injectable and ophthalmic pharmaceutical products. This characteristic is imparted to the product by virtue of the type of manufacturing process. If during the process, all components, solutions and equipment are pre-sterilized and assembled aseptically, that is, using techniques which exclude microorganisms, the product is deemed an "aseptic fill". Other injectable products, in addition to the aseptic processing, undergo sterilization when in the final container, typically using steam under pressure. This procedure, if properly designed and executed, results in a terminally sterilized product.
One solution to the problems incurred through human contamination is through automation of the processing procedure. A paper entitled, "A Robotics System for the Sterility Testing of Injectables," Barbara J. Zlotnick and Michael L. Franklin, Pharmaceutical Technology, May 1987, describes a robotics system for sterility testing of vials. According to this paper a robot is used to perform sterility testing and minimize the manipulations performed by the analyst, thereby reducing the potential for technical contamination attributable to personnel. Since human intervention is minimized during testing, the environment of the test remains cleaner with respect to viable particulate matter. There is a lower level of human activity and less potential for contamination from shedding or from disruption of the laminarity of the air flow under the hood. A cleaner environment can then be-used for a greater proportion of the work day.
In general, robotics dispensing devices known in the art include a dispensing apparatus comprising a base, and a robot device on the base. A number of stations are located on the base which cooperate with the robot device in a sequence of operations such as to produce a measured pharmaceutical dose from a supply of pharmaceutically acceptable substances. Robotics dispensing apparatus systems are used for the rapid and efficient processing of a wide variety of pharmaceutical products, as well as perform various mechanical functions. Further, use of the robot device provides an efficient manner in which to maintain a sterile environment to produce the pharmaceutical products.
The transporting of articles via pneumatic tubes is old and well known. Basically, an object is placed within a container which is then transported by air under either positive or negative pressure from one destination to another. The transport is moved within a closed tube. The interior of the closed tube and the outer dimension of the carrier form a seal, so that the carrier can be propelled between the destinations by a vacuum. Pneumatic tube systems known in the art include a closed continuous passageway having a predetermined inner cross-sectional dimension where the passageway includes a plurality of curves or bends having a predetermined radius. A fluid, such as air, is controllably forced through the passageway in a loop to move a carrier through the passageway. In order for the carrier to move freely through the passageway, the dimensions, and in particular the length, of the carriers being used have been limited by the inner cross-sectional dimension and curvature radius of the passageway.
Pneumatic delivery systems are used extensively for the rapid and efficient transportation of a wide variety of articles. These delivery systems are used in a number of business operations, including banks, hospitals, office buildings, industrial plants, and truck terminals as a few examples.
One area of commerce which currently uses the pneumatic tube and the transporting of material via the pneumatic tube on a fairly regular basis is the hospital or biomedical research/manufacturing industry. One particular application of this technology is in the area of transporting blood samples, medicines, intravenous bags, viral samples or other biological or chemical matter between locations within a hospital or laboratory. In that environment, for example, test tubes or vials of liquids are placed within a tube carrier, and are typically secured by foam or clamps within the carrier. The purpose of securing the samples (which are often contained within glass test tubes with rubber stoppers) is to help prevent breakage. When glass breaks or stoppers become dislodged (as can happen when hospital workers fail to properly secure the stoppers in the first place), chemical or biological substances can leak into the interior of the carrier. In turn, said substances can leak out of the interior of the carrier, thereby contaminating the interior walls of the tube system.
The vials or vessels of liquids, solids or gases within the carrier can move or shift during transport, which can also lead to breakage. This problem is especially acute, as the carriers are often traveling at speeds in excess of 25 feet per second. Because of the rapid acceleration and deceleration of pneumatic tube carriers, the carrier contents can easily become dislodged, and can break within the carrier, if not for clamps, foam securing means, and the like. Nonetheless, accidents can happen, whereby despite the best efforts toward securing or protecting the interior vessels, they can break, or their stoppers can become dislodged. In fact, dislodged stoppers are a primary problem, due mainly to workers who may inadvertently fail to secure them properly.
Carriers for use in the present automated pneumatic tube system come in a wide range of sizes and shapes to accommodate the physical articles to be transported in the system. As an example, pneumatic carriers are provided for transporting cash, messages, stock transaction slips, letters, blueprints, electronic data processing cards, x-rays, pharmaceutical supplies, blood samples, narcotics, viral and bacteria cultures, and a variety of other small physical objects.
Various mechanisms have previously been utilized as closure devices for pneumatic tube carriers. For example, many such carriers include an end cap that is hinged with respect to a cylindrical hull on one side of the hull and which has a latch that fastens the end cap to the opposite side of the hull in a closed position. Such carriers employ a variety of fasteners, such as snap fasteners, elastic straps with holes that fit over hooks, or straps that may be secured to bendable posts.
Side opening pneumatic tube carriers are also well-known. One conventional form of such a carrier employs two generally semi-cylindrical sections that are hinged along one longitudinal edge. The hinged sections may be swung toward or away from each other to effectuate opening and closing of the carrier hull. Locking is achieved by virtue of the end caps, which may be twisted to effectuate threaded engagement of the caps onto the carrier hull ends when the hinged hull sections have been closed. That is, the end caps are rotated in such a fashion as to be drawn towards each other onto the ends of the hull, thereby immobilizing the hull sections relative to each other. Rotation of the end caps in the opposite direction releases the hull sections and allows them to be opened.
A particularly preferred configuration comprises a side opening carrier, wherein the two sides are hinged together, and the two sides are held together when the carrier is closed by use of a hook, or detent or indented type locking lip. Such carriers include latching mechanisms to prevent the door from coming ajar or opening during transit, which could cause the carrier to become lodged in the pneumatic tubes and would also allow the contents of the carrier to spill out into the tube system. In addition, the instructions for latching such side opening containers or carriers are simple to follow, so that the container can be easily placed within the tube system. Such hinging and locking mechanisms make waterproofing or sealing the carrier a particularly difficult task, as the hinges and locks are embedded within the mold of the carrier, which is generally formed of plastic.
In another type of side opening pneumatic carrier, the access to the carrier is gained by simultaneously pulling and twisting the ends of the carrier to allow the side opening door to be opened. The instructions for such a two-step process are often difficult for many users to follow, and the physical effort and manual dexterity needed to simultaneously pull and twist both ends of the carrier against a spring resistance is often troublesome for many hospital workers. The pneumatic carrier is preferably easily opened and have a supplemental sensor mechanism to indicate that abnormal interior conditions have developed.